The present invention relates to a method for fabricating a semiconductor device and, more particularly, to a binary mask, a method for fabricating the binary mask, and a method for fabricating a fine pattern of a semiconductor device using the binary mask.
As a semiconductor device is more highly integrated, the size of a pattern realized in a semiconductor device reduces. Accordingly, the size of a pattern formed on a photomask also gradually reduces. Recently, a design rule for forming a fine pattern requires a critical dimension (CD) tolerance of approximately 2 nm. To overcome a resolution limitation, a photolithography process uses short wavelength light or uses an attenuated phase shift mask (PSM) controlling the phase of light through destructive interference alleviating an unnecessary diffraction effect.
Meanwhile, the attenuated PSM performs a CD correction process to meet a CD tolerance required for a fine pattern by a design rule. For the CD correction process, a phase shift layer and a light blocking layer are formed on a transparent substrate. Light blocking layer patterns are formed using resist layer patterns formed by a lithography process. The CD of the light blocking layer patterns is measured, the light blocking layer patterns are additionally etched to correct the CD of the light blocking layer patterns, and then exposed portions of the phase shift layer are etched using the corrected light blocking layer patterns as an etch mask to form phase shift layer patterns.
Generally, a PSM includes phase shift layer patterns having transmittance of approximately 6% with respect to short wavelength light. Recently, an ArF immersion lithography is performed to form a fine pattern of approximately 50 nm or less. Since a PSM in the ArF immersion lithography has a reduced resolution due to increased polarization effect and vector effect, a binary mask rather than the PSM is in current favor. However, the binary mask, including light blocking layer patterns still has a difficulty in meeting a CD error tolerance and CD uniformity required for forming a fine pattern. Also, to obtain a CD error tolerance and CD uniformity required during a process of fabricating the binary mask, a CD correction process applied to the binary mask should be additionally performed. In case of a binary mask including light blocking layer patterns, a hard mask material layer preventing a light blocking layer from being damaged by etching selectivity should be additionally deposited to perform the CD correction process. Accordingly, as the hard mask material layer is added, new processes related to a process condition and process equipment setting are required, and also, manufacturing cost and time for the mask increase.